1. Technical Field
The present invention relates to a mount structure in which a semiconductor device composed of a light-emitting device or a light-receiving device is mounted on a wiring board, an illumination apparatus that includes the mount structure, and a liquid crystal apparatus that includes the illumination apparatus as a backlight apparatus.
2. Related Art
A liquid crystal apparatus of a transmissive or transflective type includes an illumination apparatus 8 disposed on a back surface side of a liquid crystal panel. In the illumination apparatus 8, a light-emitting device 3 illustrated in FIGS. 8A and 8B is used in a mount structure 7 and mounted on a first surface 71a side of a flexible wiring board 70. An optical axis L of the light-emitting device 3 is oriented in a direction extending along a board surface of the flexible wiring board 70. In a light-guide plate 6, a lateral end surface that faces a light emission center 3c of the light-emitting device 3 serves as a light incidence portion 61a and light rays incident from the light incidence portion 61a are emitted from a light emission surface 6a facing in the same direction as a second surface 71b side of the flexible wiring board 70, as illustrated by arrow L1 in FIG. 8A (refer to JP-A-2008-9038).
In the illumination apparatus 8, as illustrated in FIGS. 8B, 8C, and 8D, on the first surface 71a side of the flexible wiring board 70, a first pad 75 is formed at a position beneath a first terminal 35 of the light-emitting device 3 and a second pad 76 is formed at a position beneath a second terminal 36 of the light-emitting device 3 on the opposite side of an imaginary center line L0 with respect to the first pad 75, the imaginary center line L0 extending along the optical axis L.
However, in the flexible wiring board 70 illustrated in FIGS. 8C and 8D, there is a large region in which a conductive layer is not formed at a position beneath the light-emitting device 3 in plan view and there is only a thin base film 74 in that region. Consequently, in the mount structure 7 illustrated in FIG. 8, there is a problem in that a large amount of light leaks through the base film 74 of the flexible wiring board 70, as illustrated by arrow L2. Having said that, disposing a light-shielding member on the second surface 71b side of the flexible wiring board 70 is not preferable since the thickness of the mount structure 7 would be increased.
Here, as illustrated in FIGS. 9A, 9B, 9C and 9D, the inventors of the present application have proposed forming a first light-shielding conductive layer 77a and a second light-shielding conductive layer 77b by using the same conductive layer as the first pad 75 and the second pad 76 on either side of the imaginary center line L0 and narrowing the region in which a conductive layer is not formed in the flexible wiring board 70.
However, it was found that leakage of light illustrated by arrow L2 in FIG. 9B could also not be prevented with the mount structure 7 illustrated in FIG. 9. As various measured results of this phenomenon, it was found that not only was a light-shielding property not imparted at positions beneath the light emission center 3c of the light-emitting device 3 in plan view but also that leakage of light through the base film 74 could not be prevented.
As for this phenomenon, in the case where, instead of the light-emitting device 3, a light-receiving device is mounted such that the optical axis thereof is oriented in a direction extending along the board surface of the flexible wiring board 70, a problem arises in that, light that leaks through the base film 74 of the flexible wiring board 70 is incident on the light reception center of the light-receiving device.